Engine brake

ABSTRACT

A CONTROL FOR CONVERTING A POWER PRODUCING INTERNAL COMBUSTION ENGINE INTO A POWER ABSORBING AIR COMPRESSOR IS DISCLOSED. THE CONTROL INCLUDES ROTATABLE CAMS POSITIONED BETWEEN INJECTOR ROCKER ARM ACTUATING BOSSES AND CORRESPONDING STRUCTURE ON THE EXHAUST VALVE ROCKER ARMS. FLEXIBLE COUPLING IS PROVIDED BETWEEN THE INDIVIDUAL CAMS AND THE ACTUATING MECHANISM WHEREBY RAPID RESPONSE OF THE CONTROL IS ACHIEVED AND MOVEMENT OF THE CAMS INTO AND OUT OF OPERATIVE POSITION IS ACHIEVED AT THE PROPER TIMES THROUGH A MECHANISM WHICH REMEMBERS THE DESIRED OPERATIVE MODE.

March 23, 1971 Filed May 2:5} 1969 F. W. STAGER ENGINE BRAKE FIG. 2

2 Sheets-Sheet l INVENTORS ROBERT N. MINOR FRANCIS W.'STAGER F/SHMA/V 8 VAN KIRK ATTORNEYS March 231971 F. w. STAGERYET'AL I 3,572,300

ENGINE BRAKE Filed May 25, 1969 2 Sheets-Sheet 2 40 c, 4 5; l w 46 INVENTORS F/SHMA/V a m KIRK ATTORNEYS 3,572,300 ENGINE BRAKE Francis W. Stager and Robert N. Minor, Stalford Springs, Conn., assignors of a fractional part interest to Thomas Minor, Crystal Lake, Conn.

Filed May 23, 1969, Ser. No. 827,227 Int. Cl. F02d 9/00 US. Cl. 123-97 15 Claims ABSTRACT OF THE DISCLOSURE A control for converting a power producing internal combustion engine into a power absorbing air compressor is disclosed. The control includes rotatable cams positioned between injector rocker arm actuating bosses and corresponding structure on the exhaust valve rocker arms. Flexible coupling is provided between the individual cams and the actuating mechanism whereby rapid response of the control is achieved and movement of the cams into and out of operative position is achieved at the proper times through a mechanism which remembers the desired operative mode.

BACKGROUND OF THE INVENTION (1) Field of the invention The present invention relates to the braking of internal combustion engines. More specifically, this invention is directed to apparatus which, when operative, will convert a power producing internal combustion engine into a power absorbing air compressor or pump. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.

(2) Description of the prior art While not limited thereto in its utility, the present invention is particularly well suited for installation on multi-cylinder twoor four-cycle compression ignition engines. Such prime movers are commonly known as diesel engines and, on each cylinder, employ rocker arms and associated push rods for opening the exhaust valves and for causing operation of a fuel injector in the proper timing sequence. As is well known in the art, the diesel powered vehicle is afforded substantially no braking from its engine. In fact, even in the idle mode there is a return of substantial energy to the engine pistons during the expansion stroke of the cycle. Accordingly, a problem of long standing in the art resides in the provision of adequate braking for diesel powered vehicles. Due to brake overheating and/ or exhaustion of the compressed air sup ply for the brakes in excess of its replenishment rate, it is undesirable at best to rely upon the vehicle braking system to prevent overspeed during the descent of long grades.

In order to minimize brake wear and obviate the danger of accidents resulting from brake failure, several systems have been proposed for converting internal combustion engines from normal power operation to braking operation. Thus, there are systems available which, for example, will convert a vehicle installed internal combustion engine to an air pump or compressor either at the operators command or automatically when the vehicle power lever is returned to the idle position. This conversion, as is well known in the art, may be achieved by reducing or shutting off the supply of fuel to the engine while simultaneously advancing the operation of the exhaust valves to thereby cause the exhaust valves to open at or near the end of the compression strokes of'their associated pistons. The prior art conversion systems have, for the reasons to be discussed briefly below, not been United States Patent Office 3,572,300 Patented Mar. 23, 1971 entirely successful. The approaches taken in the prior art have included axial or rotary shift of the engine cam shaft, the installation of complicated linkages or mechanisms to operate the exhaust valves independently of the cam shaft or the utilization of special bypass ports.

All of the above briefly mentioned prior art control schemes for converting a power producing internal combustion engine to a power absorbing compressor have suffered from one major and common deficiency. These the valves into the piston is the fact that the exhaust valves and valve seats were often burned as a consequence of use of the prior art conversion systems. Valve burning resulted from improper timing of the conversion system control whereby the exhaust valves were opened with excessive fuel in the cylinder. This condition would occur, for example, when the operator desired to terminate braking and stepped on his accelerator. Prior art controls have not reacted quickly enough, especially in cold weather, to disable the means which were'opening the exhaust valves during the air pump mode of operation.

Additional disadvantages of the prior art systems re sided in their relative complexity and the necessity for using precision components; both of which characteristics resulted in comparatively expensive apparatus. Coupled with the initial apparatus cost, in the prior art, has been a relatively high installation cost. Additional installation problems have been presented by the fact that both the weight and configuration of the prior art controls have either prevented installation on many engines or have required substantial modification in order to permit retrofit of the controls. Once installed, the prior art engine brake controls have been extremely diflicult to adjust so as to attempt to achieve maximum braking efficiency and, partly for the reasons discussed above, have often caused excessive wear on engine components. Due to the complexity of the prior art controls, the maintenance requirements therefore have been comparatively expensive. These maintenance requirements have been particularly troublesome in those systems which relied, for actuating power, on engine oil pressure.

SUMMARY OF THE INVENTION The present invention overcomes the foregoing and other disadvantages of the prior art by providing a novel engine brake control. The numerous objects and advantages of the present control will become apparent from a study of the detailed description thereof below.

The control system of the present invention includes, on each bank of cylinders, a rack which is driven by a suitable actuator. The rack actuator is energized, either by a driver operated switch or automatically by fuel rack motion, when the power level is returned to the idle fuel position. A plurality of pinion gears, one for each cylinder, will be mounted in the supporting channel for the rack and will engage the rack. These pinion gears will be caused to rotate upon energization of the actuator to drive the rack. Actuating cams having a major and a minor width will be flexibly coupled to the pinion gears and, upon rotation of the gears, the cams will also rotate so as to present their major width between actuating members mounted on the exhaust valve and fuel injector rocker arms. Accordingly, in the operative position, the actuating cam will mechanically couple the injector rocker arm to the exhaust valve rocker arm and the upward motion of the injector push rod will cause opening of the exhaust valve. At other times, that is with the control of the present invention in the unenergized state, the minor width of the actuating cam will be disposed between the injector rocker arm and exhaust rocker arm actuating members and thus injector push rod motion will not be coupled to the exhaust valve rocker arm.

It is especially to be noted that, due to timing variances between cylinders, not all of the actuator cams will be able to rotate at the time their pinion gears rotate 90 under action of the rack and rack drive actuator. Due to the flexible coupling between the pinion gears and actuating cams, a torsional force will be imposed on the cams and the cams will thereupon rotate into and out of position as the proper timing events for each cylinder occur.

BRIEF DESCRIPTION OF THE DRAWING The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawing wherein like reference numerals refer to like elements in the various figures and in which:

FIG. 1 is a top view, partially in section, of the present invention as installed on a bank of three cylinders of a compression ignition engine.

FIG. 2 is a partial side elevation view, taken along line 2-2 of FIG. 1, depicting a typical rotary actuating mechanism as may be used with the present invention.

FIG. 3 is a cross-sectional top view, taken along line 3-3 of FIG. 4, of an actuating cam for use with the present invention.

FIG. 4 is a side elevation view, partly in section, of the present invention with the exhaust valve actuating mechanism in the inoperative position; the view in FIG. 4 being taken along line 44 of FIG. 1.

FIG. 5 is a cross-sectional side elevation view similar to FIG. 4 but showing the actuating cam rotated to the operative position.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference now to FIG. 1, an engine head riser of a conventional diesel engine is indicated at 10. Removal of the-rocker cover exposes the valve and fuel injector operating mechanisms mounted on the engine block within riser 10. FIG. 1 may be considered to depict a threecylinder straight engine or a single bank of three cylinders of a six-cylinder engine with the engine valve springs indicated in phantom at 12. Each engine cylinder will be provided with a pair of exhaust valve rocker arms, indicated respectively at 14 and 16. Each cylinder will also be provided with an injector rocker arm 18. The timing and operation of the push rods for the rocker arms on each cylinder by means of the engine cam shaft is well known in the art and will not be described herein. It is, however, to be noted that under normal adjustment and operation the fuel injector plunger for each cylinder, which is connected to its respective injector rocker push rod through an injector rocker arm, will be operated when the piston in the associated cylinder nears the end of the compression stroke, the injector push rod following through the stroke of the piston. Restated, in order to prevent preignition, fuel injection occurs slightly after the top dead center piston position and is accomplished when the force transmitted from the injector push rod becomes sufficient to overcome the spring bias in the injector valve mechanism. As previously noted, in order to achieve maximum efficiency of the engine when operated as an air pump or compressor, the exhaust valves should be opened when their associated piston reaches the top dead center position.

In accordance with the present invention, a channel 20 is mounted on the engine block above and transverse to the rocker arms. In accordance with the simplified 4 installation permitted by the present invention, the channel 20 may be installed using the rocker arm pedestal bolts 22 with which the engine is equipped.

The channel 20 supports, as may best be seen from FIGS. 4 and 5, a U-shaped guide channel 24. Guide channel 24 will typically be bolted to support channel 20. For the purpose to be described below, a rack 26 will be positioned for limited movement along guide channel 24.

Considering again FIG. 1, an actuating mechanism, indicated generally at 28, will be mounted on the exterior of guide channel 24 by any suitable means. In FIGS. 1 and 2. the actuating mechanism 28 is illustrated as a rotary solenoid having an output shaft which is keyed to a pinion gear 30 disposed within guide channel 24. Pinion gear 30 engages rack 26 and, accordingly, energization of the actuating mechanism 28 will cause rack 26 to move along guide channel 24. It is especially to be noted that means other than a rotary solenoid may be employed as a drive mechanism for pinion gear 30. Thus, pinion gear 30 may also be driven, through suitable gearing, by longitudinally movable means such as a pneumatic or a hydraulic cylinder. It is also to be noted that to minimize the driving force needed for movement of rack 26, and also to minimize wear, the portions of rack 26 which ride against the inner walls of guide channel 24 may be coated with a suitable low friction material such as Teflon.

Referring again to FIG. 1, rack 26 will engage a plurality of additional pinion gears 32 which are also disposed in guide channel 24; there being one of such additional pinion gears 32 for each engine cylinder. While not absolutely necessary, in the interest of ease of adjustability it has been found desirable to make pinion gears 32 adjustable. In the disclosed embodiment, adjustability is accomplished by means of splitting the gears and providing a tightening screw 34 whereby the gears may be properly positioned with relation to the pinion shafts 36 and thereafter clamped tightly thereto. The gears 32 will typically be spaced from the inner top and bottom walls of guide channel 24 by suitable spacer means such as, for example, washers 37.

The pinion shafts 36, as may best be seen from FIGS. 4 and 5, extend completely through guide channel 24. The pinion shafts 36 are shown as being slotted and held in position by retaining rings 38 on the exterior top and bottom surfaces of guide channel 24. It has, however, been found that the retaining rings may be eliminated since the clamping of the pinion gears onto the shafts will prevent vertical movement of the shafts.

While not essential, it has been found useful to thread the lower ends of pinion shafts 36 as shown. In addition, for the purposes to be described below, a small hole, not shown, is drilled in each of the pinion shafts adjacent the inwardly disposed end of the threads. A cam spring 40 is screwed onto the threaded end of each of pinion shafts 36. Springs 40 will have a hooked end which will be engaged with the aforementioned holes in the pinion shafts. Accordingly, the springs 40 will be unable to rotate relative to their pinion shafts 36. As will be apparent from the description below, the springs 40 will have very little load thereon and stainless steel springs have been employed successfully. It will also become obvious, from the description of the operation of the invention, that springs 40 and cams 42 function as a memory device, albeit a memory with fast reaction time, which insures proper timing of the operation of the invention.

The other ends of springs 40 will engage threaded projections on actuating cams 42. The shape of the actuating cams may best be seen from a simultaneous consideration of FIGS. 3 and 4. The threaded cam projections will, like the threaded ends of pinion shafts 36, be provided with a drilled hole into which hooks on the other ends of springs 40 will be inserted. As may be seen from FIG. 3, cams 42 have a minor width AA and a major width B-B. In the brake inoperative position of FIG. 4,

that is with the rack driving mechanism 28 in its unenergized state, the cams will be positioned whereby their minor width AA will be disposed between an actuating boss 44 on the injector rocker arms 18 and oppositely disposed actuating means on the exhaust rocker arms 16.

The injector rocker arms 18 may be forged with an actuating boss 44 thereon or, in the case of a retrofit, a boss can be welded to the arms. It is to be noted that boss 44 is provided with a radius on the side thereof which will, when the engine brake is in operation, contact a cam 42. The radius on boss 44 provides a changing contact point whereby the actuating boss will not grip a corner of cam 42. This changing contact point eliminates the need to replace or reshape the injector rocker arm actuating boss when new cams are inserted or when the exhaust rocker actuating mechanism, to be described below, changes position such, as for example, may occur after a valve grinding operation.

The actuating mechanism on the exhaust valve rocker arms 16, in the embodiment shown in FIGS. 4 and 5, comprises an adjustment screw 46 which passes through a threaded hole in an actuating bossv 48; an actuating boss 48 being formed on or affixed to the inwardly disposed side of each of exhaust rocker arms 16 in the same manner as the injector actuator boss 44 is provided on the injector rocker arms. It is to be noted that the adjustment screws 46 may be eliminated in cases where the actuating bosses 44 and 48 are provided on their respective rocker arms by the engine manufacturer.

Under normal engine operation, with the vehicle operator calling forthe injection of fuel, the engine will be operating as a power producer. Under these normal conditions the actuating mechanism 28 Will be in the deenergized state and the earns 42 wil be positioned as shown in FIG. 4. Accordingly, the cams 42 will be rotated so as to present their minor width AA between their respective injector rocker arm actuating boss 44 and the head of an adjustment screw 46 or an actuating boss 48 on their respective exhaust rocker arms 16. The dimensions of earns 42 are such that, with the control in the FIG. 4 condition, upward motion of the inejctor push rods 50 will not be coupled to the exhaust rocker arms; there being a gap between the injector actuating bosses 44 and the facing surfaces of cams 42 regardless of the position of the injector push rods.

When it is desired or necessary to convert the power producing engine into a power absorbing air compressor, the actuating mechanism 28 will beenergized. Energization of mechanism 28 may be accomplished either automatically, through a suitable connection to the fuel rack, or via a vehicle operator actuated switch. In either event, energization of actuating mechanism 28 will, via pinion gear 30, drive rack 26 along guide channel 24. Movement of the rack will, in turn cause 90 rotation of each of pinion gears 32. The movement of pinion gears 32 will be transmitted to the springs 40 affixed to the pinion shafts 36. The springs 40 will thus exert a torsional force on the actuating cams 42 and the cams will attempt to turn from the inoperative position of FIG. 4 to the operative position of FIG. 5. However, due to timing variances between the cylinders, not all of the cams will be able to rotate when the command to convert to air compressor operation is generated. Those cams which, due to instantaneous injector actuating boss position, are not able to complete- 1y rotate as their associated pinion gear rotates will, accordingly, be biased by springs 40 and the springs will function as memory devices which will snap the cams 42 into position as the proper timing events for each cylinder occur. Restated, as a result of the flexible coupling between the actuating mechanism and the actuating earns 42, the control mechanism will remember that a command to convert to compressor operation has been received and will wait for correct engine timing (injector push rods down) to rotate each cam into position to actuate the exhaust valve rocker arms to open the exhaust Valves.

FIG. 5 shows one of cams 42 as rotated so as to present its major width B'B between an injector rocker arm actuating boss 44 and the head of an adjustment screw 46 which forms a part of the exhaust rocker arm actuating mechanism. With the cam in the position shown in FIG. 5, upward motion of the injector push rods 50 will be mechanically coupled to the exhaust rocker arm and will cause depression of the exhaust valve operating mechanism. Through proper sizing of the cams 42, the exhaust valves may be caused to open, during the upward movement of the injector push rods, precisely when the pistons reach their top dead center position. Opening of the exhaust valves will release compressed air from the cylinders into the engine exhaust manifold and thus the engine will absorb power while in the idle mode and will provide braking action.

When it is desired to terminate braking action, the actuator 28 will be deenergized and the rack '26 will be driven back to its initial position. The return of the rack 26 to its original position will cause the pinion gears 32 to rotate in the opposite direction and also return to their original position. The return of the pinion gears 32 to their starting position will again impose a torsional force on springs 40, but in the opposite direction to the energizing force. The cams 42 will, accordingly, individually return to their original or inoperative position as the proper timing sequence occurs. It is especially to be noted that the return of the cams 42 to the position shown in FIG. 4 will occur at the proper time for each cylinder; that is, when each injector push rod has returned to the down position thereby releasing the cam from the clamped position between the injector rocker arm boss 44 and the actuating mechanism on the exhaust rocker arm. The ac tion of the present invention on return to normal power producing engine operation is not only sure and fast, but valve burning problems are obviated since the coupling between the injector mechanism and the exhaust valve mechanism for each cylinder will automatically be terminated with the injector push rods in the down position and before fuel can be injected into the cylinder.

While a preferred embodiment has been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the present invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.

What is claimed is:

1. Apparatus for selectively operating an internal combustion engine in a power producing or a power absorbing mode, the engine including a plurality of fuel delivery means and a plurality of exhaust valves and exhaust valve actuating means operating in timed sequence with pistons in a plurality of cylinders, said apparatus comprising:

control means movable between positions commensurate with the power producing and absorbing modes;

cam means associated with each cylinder for mechanically coupling motion of the fuel delivery means for each cylinder to the exhaust valve actuating means of the corresponding cylinder when said control means has moved to the position commensurate with power absorption; and

means flexibly coupling said control means to said cam means whereby said cam means associated with each cylinder will independently follow the movement of said control means.

2. The apparatus of claim 1 wherein said cam means comprises:

rotatable cams having a major and a minor Width, said major width being commensurate with power absorbing operation of the engine.

3. The apparatus of claim 1 further comprising:

an actuator projection on and moving with the fuel delivery means for each cylinder; and

an actuator projection on and moving with the exhaust valve actuating means for each cylinder, said cam means coupling fuel delivery means actuator projections to exhaust valve actuator projections of corresponding cylinders when in the power absorption mode position.

4. The apparatus of claim 3 wherein said cam means COITIPI'ISESZ rotatable cam having a major and a minor width, said major width being commensurate with power absorbing operation of the engine.

5. The apparatus of claim 1 wherein said control means comprises:

a plurality of rotatable members, said members being connected to said flexible coupling means; and

means for simultaneously rotating said rotatable members 90 into and out of the position commensurate with power absorption mode.

6. The apparatus of claim 5 wherein each of said rotatable members comprises:

a shaft connected to said flexible coupling means; and

an adjustable pinion gear mounted on said shaft and driven by said rotating means.

7. The apparatus of claim 5 further comprising:

an actuator projection on and moving with the fuel delivery means for each cylinder; and

an actuator projection on and moving with the exhaust valve actuating means for each cylinder, said cam means coupling fuel delivery means actuator projections to exhaust valve actuator projections of corresponding cylinders when in the power absorption mode position.

8. The apparatus of claim 7 wherein said cam means comprises:

rotatable cams having a major and a minor width, said major width being commensurate with power absorbing operation of the engine.

9. The apparatus of claim 8- wherein said rotating means comprises:

a rack in engagement with said rotatable members; and

means for driving said rack.

10. In a compression ignition engine, said engine having a plurality of cylinders and means for injecting fuel into each cylinder and for valving exhaust gases from each cylinder, said injecting means including a rocker arm coupled to the engine cam shaft and said exhaust valving means including a rocker arm coupled to the engine cam shaft, an engine brake control comprising:

means mounted on said engine and movable between positions commensurate with power producing and braking modes;

a plurality of rotatable cam means for coupling fuel injector rocker arm motion to an associated exhaust valve rocker arm only in the braking mode; and

means connected to said movable means for independently rotating said cam means between power producing and braking positions, said cam rotating means storing desired cam means position and causing rotation of said cam means at the proper time for each cylinder.

11. The control of claim 10 wherein said connecting means comprises:

spring means for flexibly coupling said movable means to each of said cam means.

12. The apparatus of claim 11 wherein said cam means comprises:

rotatable cams having a major and a minor width, said major width being commensurate with braking mode.

13. The apparatus of claim 12 further comprising:

an actuating boss on each of said injector rocker arms;

and

actuating means on and moving with each of said exhaust valve rocker arms, said cams being positioned between said boss and actuating means on each cylinder. 14. The apparatus of clam 13 wherein said movable means comprises:

a plurality of rotatable members, said members being connected to said flexible coupling means; and

means for simultaneously rotating said rotatable members '90 into and out of position commensurate with the braking mode.

15. Apparatus for selectively operating an engine in either a power producing or power absorbing mode, the engine including at least one piston and cylinder assembly having a combustion chamber, an exhaust valve for exhausting gas from the combustion chamber and fuel delivery means and exhaust valve actuating means which operate in timed sequence with the piston, comprising:

control means movable between positions commensurate with the power producing and absorbing modes; cam means for mechanically coupling the operation of the fuel delivery means to the exhaust valve actuating means when said control means has moved to the position commensurate with power absorption; and

means resiliently coupling said control means to said cam means whereby the cam means may resiliently follow movement of said control means.

References Cited UNITED STATES PATENTS 1,547,130 7/1925 Robinson 12397B 1,637,118 7/ 1927 Kirchensteiner 12397B 2,002,196 5/1935 Ucko 12397B 2,197,282 4/1940 Walker 12397B 3,405,699 10/1968 Laas 123-97B 3,439,662 4/1969 Jones et al 12397B 3,332,405 7/ 1967 Haviland 123-97B FOREIGN PATENTS 405,196 2/1934 Great Britain l23-97B WENDELL E. BURNS, Primary Examiner 

